Deriving accurate surface gravity values for planet host stars … · 2014-10-16 · Deriving...
Transcript of Deriving accurate surface gravity values for planet host stars … · 2014-10-16 · Deriving...
Deriving accurate surface gravityvalues for planet host stars
Annelies Mortier
Nuno C. Santos, S.G. Sousa, V.Zh. Adibekyan, I.M. Brandao
Towards Other Earths IIThe Star-Planet Connection
17 September 2014, Porto
Deriving accurate surface gravityvalues for planet host stars FGK dwarfs
Annelies Mortier
Nuno C. Santos, S.G. Sousa, V.Zh. Adibekyan, I.M. Brandao
Towards Other Earths IIThe Star-Planet Connection
17 September 2014, Porto
Outline
1 Introduction
2 Deriving stellar parametersMethodLine list
3 Surface gravity determinationTransitsAsteroseismologyCorrection formulaeCompare with IRFM
4 Conclusions
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Introduction
Precise, homogeneous, and accurate stellar parameterscrucial in astronomy
�1.0 �0.8 �0.6 �0.4 �0.2 0.0 0.2 0.4[Fe/H]
0.00
0.05
0.10
0.15
0.20
0.25
Rela
tive
freq
uenc
y
exponential [Fe/H], linear masswith constantwith drop + cteHARPS
(Pepe et al. 2013) (Mortier et al. 2013)
Stellar and planetary characterization – Star-planetconnection – Galactic evolution – . . .
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Introduction
(Torres et al. 2012)
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Spectroscopic analysis: high-resolution spectroscopy
Spectral synthesis
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Spectroscopic analysis: high-resolution spectroscopy
Individual spectral line analysis
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FGK stars - Method overview
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FGK stars - Method overview
Masses and radii
Dwarfs: corrected Torres et al. (2010) calibration(Sub)giants: Padova stellar evolutionary models
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Carefully chosen stable line list set
-400
-200
0
200
4500 5000 5500 6000 6500
Thi
s W
ork
- SO
08
Teff (K) This Work
4500
5000
5500
6000
6500
Tef
f (K
) SO
08
<∆Teff
>=-31 K
σ=53 K
-400
-200
0
200
4400 4600 4800 5000
IRFM
- T
eff (
K)
Teff (K) IRFM
(Tsantaki et al. 2013)
Sousa et al. (2008) for stars with Teff > 5200 K
Tsantaki et al. (2013) for stars with Teff ≤ 5200 K
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SWEETCat
(Santos et al. 2013)
Catalogue of homogeneously derived parameters for planet hosts
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Surface gravity from photometric transit
90 transit hosts analysed
3.8 4.0 4.2 4.4 4.6 4.8 5.0loggspec
3.8
4.0
4.2
4.4
4.6
4.8
5.0
logg L
C
mean ∆logg = -0.12σ = 0.26
ρ∗ + k3ρp =
3π
GP2
(
a
R∗
)3
Spectroscopic surface gravitynot well constrained.
Transit light curve surfacegravity more precise and
accurate
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Marginal effect on temperature and metallicity
−0.8 −0.6 −0.4 −0.2 0.0 0.2 0.4∆logg
−600
−400
−200
0
200
400
600
∆ T
eff
−0.8 −0.6 −0.4 −0.2 0.0 0.2 0.4∆logg
−0.4−0.3−0.2−0.1
0.00.10.20.30.4
∆ [F
e/H]
Mean differences
19 K and 0.02 dex
Mean absolute deviation
66.5 K and 0.03 dex
Systematic, but smalltrends, even for very large
logg differences
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Transit logg may also be inaccurate (Huber et al. 2013)
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Surface gravity from asteroseismology
86 FGK stars analysed
3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0loggspec
3.4
3.6
3.8
4.0
4.2
4.4
4.6
4.8
5.0
logg s
eis
Use large separation ∆ν,maximum frequency νmax ,effective temperature Teff ,metallicity [Fe/H], andPARSEC isochrones
Asteroseismic surface gravitymore precise and accurate
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Marginal effect on temperature and metallicity
−1.2 −1.0 −0.8 −0.6 −0.4 −0.2 0.0 0.2∆logg
−600
−400
−200
0
200
400
600
∆Teff
−1.2 −1.0 −0.8 −0.6 −0.4 −0.2 0.0 0.2∆logg
−0.4−0.3−0.2−0.10.00.10.20.30.4
∆[Fe/H]
Mean differences
68 K and 0.04 dex
Mean absolute deviation
28.5 K and 0.02 dex
Same systematic, but smalltrends as with the transit
sample
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Linear correction formula
4500 5000 5500 6000 6500 7000Teff
−1.0
−0.5
0.0
0.5
1.0
∆logg
y=(−4.57±0.25) ·10−4 ·x+(2.59±0.15)
5000 5500 6000 6500 7000Teff
−1.0
−0.8
−0.6
−0.4
−0.2
0.0
0.2
0.4
∆logg
y=(−3.89±0.23) ·10−4 ·x+(2.10±0.14)
Correcting for the spectroscopic logg will not make it more precise, but itwill make it more accurate!
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Comparison with accurate IRFM
5000 5500 6000 6500 7000Teff,IRFM
5000
5500
6000
6500
7000
T eff,spec
Unconstrained
5000 5500 6000 6500 7000Teff,IRFM
5000
5500
6000
6500
7000
T eff,spec
Constrained
Our unconstrained spectroscopic results can be trusted!
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Conclusions
Precise, homogeneous, and accurate stellar parameters are crucial
Our long-standing spectroscopic method to analyse FGK stars
provides precise, accurate, and homogeneous results
Surface gravity is not well constrained by spectroscopy but by usingthe ARES+MOOG method combined with SO08+TS13 line list
set, there is only a marginal effect on the other atmosphericparameters
Planetary mass and radius differ only by 1.3 − 2%1.3 − 2%1.3 − 2% and 1 − 1.5%1 − 1.5%1 − 1.5%
Temperatures, metallicities, and microturbulences developed byour method+linelist have been proven to be consistent with variousmethods
Our spectroscopic surface gravity can be easily corrected with a
linear formula
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Conclusions
Precise, homogeneous, and accurate stellar parameters are crucial
Our long-standing spectroscopic method to analyse FGK stars
provides precise, accurate, and homogeneous results
Surface gravity is not well constrained by spectroscopy but by usingthe ARES+MOOG method combined with SO08+TS13 line list
set, there is only a marginal effect on the other atmosphericparameters
Planetary mass and radius differ only by 1.3 − 2%1.3 − 2%1.3 − 2% and 1 − 1.5%1 − 1.5%1 − 1.5%
Temperatures, metallicities, and microturbulences developed byour method+linelist have been proven to be consistent with variousmethods
Our spectroscopic surface gravity can be easily corrected with a
linear formula
Thank you!Annelies Mortier (St Andrews) Accurate loggs for FGK dwarfs 15 / 15